Energy transfer between helium metastable particles and neon

Light absorption and emission spectroscopy was used to study the time dependences of the Heᵐ(2³S), He₂ᵐ(a³Σᵤ⁺), and Neᵐ(³P₂) number densities and spectral-line emission intensities from 19 NeI states during the afterglow of helium-neon discharges. The NeI states below 20.56 eV are produced, either directly or by cascading, by excitation transfer between Heᵐ(2³S) and Ne with a reaction rate constant of 4.3×{}10^-12 cm³{s}^{{-}1}$, in agreement with previous studies. The $Ne(2{p}⁵3s)$ states are formed directly by the dissociative-excitation-transfer mechanism ${He}₂ᵐ(a³{Σ}ᵤ⁺)+Ne{→}{({He}₂Ne)}ᵣ*{→}Ne(2{p}⁵3s)+2He$ involving an intermediate repulsive state. No evidence was found for the production of ${Ne}I$ energy levels above 20.56 eV by binary energy-transfer processes.